Pneumatically-operated percussive hand-tool.



G. H. STEVENS.

PNEUMATIQALLY OPERATED PERGUSSIVE HAND TOOL.

APPLICATION FILED JULY 7, 1913.

1 1 1 O, 1 55, Patented Sept. 8,1914.

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W a d/ 4 W MW UNITED STATES PATENT OFFIQE.

CLEMENT HENRY STEVENS, 0F LAB PALMA S, GRAND CANARY, CANARY ISLANDS,

ASSIGNOR 0F ONE-HALF TO SUMMERS HUNTER, 0F WKLLSENDON-TYNE, ENG- LAND.

PNEUMATICALLY-OPEBATED PEBCUSSIVE HAND-TOOL.

Patented Sept. 8, 19141.

Application filed July 7, 1813- Serial N0- $77,750.

To all whom it may concern:

Be it known that I, CLEMENT HENRY S'rnvnns, a subject of the King of Great Britain, residing at Las Palmas, Grand Canary, Canary Islands, engineer, have invented a new and useful Improvement in Pneumatically Operated Percussive Hand- Tools of which the following is a specification.

This invention relates to pneumatically operated percussive hand tools of the type in which a piston constituting a hammer is reciprocat'ed by the admission of compressed air alternately to opposite sides of said piston, and to that class of apparatus in which the admission of compressed air to the opposite ends of the piston cylinder is controlled by means of a valve interposed between two sets of ports communicating with the opposite ends of the cylinder in which the piston or hammer works, each set of ports being alternately and automatically closed by said valve to admit air under ressure first to one end and then to the ot er end ofi said cylinder to reciprocate the piston in the latter.

According to this invention the valve is in the form of a'plate with flat faces, and these faces seat alternately on opposite sides of a valve chamber having inlet and outlet orts extending from the valve seats on mth sides of the valve. The inlet passages extend from opposite sides of the valve to a main air conduit, and the outlet passages extend from opposite sides of the valve to opposite ends of the cylinder in which the iston or hammerworks. The pressure uid acts upon the whole area of one face of the valve while passin from the inlet to the outlet passages on t e one side of the valve and closes the latter upon the inlet and outlet ports in the valve seat on the opposite side of the valve, the face of the valve on this side being now subjected to the pressure of the fluid over an area which is only that of the inlet.

A tool provided with the improved means for controlling the air supply is illustrated in the accompanying drawings, in which Figure 1 is a longitudinal section of the tool, Fig. 2 a section on the line ;c-a2 in Fig. 1. Fig. 3 is a view on the line y-y in Fig. 1, showing a plan of the upper face of the lower block in which the valve chamber is block 9.

formed, F 4 is a plan view of the upper face of the upper block and Fig. 5 is a section on the line 2--z in Fig. 3, Fig. (l is a view similar to Fig. 5 illustrating a modifi-' cation in the arrangement of the ports.

The tool comprises, as is well 'known, a handle 1 furnished with a main air valve 2 which controls the supply of air to a passa e 4 formed at one end of a socket 5. The 0t er end of this socket is screw-threaded to receive the rear end of the-cylinder 6 in which works a piston or hammer 7.

In carrying out the invention, I provide within the socket 5 and co-axially with the cylinder 6, two annular blocks 8,1 9. The upper face of the lower block 9 is formed with an elongated recess 10 to receive the valve 11 and in communication with the ends of the recess are ports or passages 12 and 12, which extend from'the upperface of the block to the floor of the recess 10. The ports 12 and 12, serve to admit air into the valve chamber 10 beneath the valve 11, which valve opens and closes an outlet port 13 formed midway of the chamber 10 in the The upper block 8 is formed with inlet ports 12 and 12 which register with the ports 12, 12, in the lower block 9 and is also formed with an inlet port l3 which is coaxial with the port 13 in the block 9. The several ports 12, 12, 12", 12, 13 and 13* are disposed to form a middle passage (18 and 13 an inner pair of passages (12 and 12), and an outer pair of passages (12 and 12). On the forward or power stroke of the pict-ion the air passes through the ports 13, 12", and 14, and on the return piston movement the air passes through the ports 12, 12, 12,and 13. The inlet port 13 is opened and closed by the valve 11, which latter controls communication between the said port and outlet ports or passages 14,14, extending upward from the lower face of the block 8 and radially to the inner periphery thereoi. To retain the upper and lower blocks 8, 9, in the roper position relatively to the ports, the ower block 9 is provided with dowels 15 which engage in corresponding recesses 16 in the block 8.

The two blocks 8, 9, placed face to face are held within the socket 5 by screwing the handle 1 upon the cylinder 6 at 17 so that the blocks'are secured between the end of ton operable in said chamber; said members provided with a recess, and having ports communicating with said piston working chamber and said passageway; and an aira controlled valve automatically erable in said recess to alternately open an close said ports whereby to operate the piston, and said piston working chamber having an exhaust opening, substantially as described.

2. In a pneumatically-operated hand tool,

'the combination of a hollow cylinder having an air chamber and a passageway leading therefrom to the head end of the cylinder; members located within said air chamber and having a plurality of registering apertures providing air ports, said ports com-- ports for admitting air to said other end of the cylinder whereby to produce variable pressure on said valve and efiect the actuation of the same during the reciprocation of the piston; and said piston working chamber having an exhaust opening, substantially as described.

3. In a pneumatically-operated hand tool, the combination of a cyllnder providing a piston working chamber and having an air chamber, and a passageway roviding communication between the air 1: amber and the piston chamber; a controlling valve-for said air chamber; a piston operable in the piston chamber; a pair of blocks located within said air chamber and having registering pairs of ports and registering ports intermediate said pairs of ports, the adjacent faces of said blocks being cut away to provide a recess providing communication between. the middle and inner air of said ports; a plate valve mounte to operate within said recess and automatically operable to open and close communication between said ports whereby to admit compressed air into said piston working chamber, and said piston chamber having an exhaust opening, substantially as described.

In witness whereof I have hereunto set my hand in the resence of two witnesses. 'CLEME T HENRY STEVENS. Witnesses:

ARTHUR E. EDWARDS,- E. LAURENCE H. Emor. 

